I want to talk about tempering

[Eisenhower]

On the topic of tempering and removal of it, my understanding is as follows:

Aether in the XIV setting possess a lot of different properties, among which there is a sort of matter-energy/aether conversion and alteration as well as aether serving as the soul of living beings. This latter function hinges on the aether having a signature unique to the being it stems from - a signature I assume defines the identity/ego of the being. From the latest patch (but probably even earlier than that, my memory is just poor) we know that Sharlayan scholars consider aether to have a wave component.

From that, I suspect that tempering modulates the base aether signature of the target. This modulation is either a directed function that processes the target aether to a new form, or alternatively, the presence of a primal-sources signature forces the conformation of a weaker signature to it (cf. prion protein conformational changes). Personally, I subscribe more to the latter of these explanations since the Garlean Empire's experiments with creating Resonant individuals appear to work in this manner (with Krile supplying the signature and the sacrifices supplying the "strength level"). Either way the new signature results in altered behaviour in the target. Since the mortal species (so far) show no inherent ability to safeguard or repair their own signatures, tempering is considered permanent.

Depending on how the aetheric signature is defined, it may be impossible to reverse the tempering effect. Although I suspect an inverse waveform (compared to original primal-derived waveform) could be used to return the signature to it's original state, it may be the case that aetheric signatures that comprise a soul aren't static in nature. The passage of time may naturally change a soul-signature in such a way that modulating in an "inverse" way have no effect, limited effect, or even cause further damage. As such, it may be necessary to generate an adapted modulating process that considers the natural changes in soul-signature aether to properly reverse tempering. But such calculations seem to be beyond the technological level of the XIV setting at the moment.

I don't think that the protection the WoL enjoys is tempering from Hydaelyn, though I recall some primals implying it being such. Rather, it may be a layer of interference that scrambles or "demotes" waveforms that originate from primals, rendering them harmless in terms of information but still being able to carry force (as shown by Arenvald was forced down but not the WoL when defending against Lakshmi). This can however be considered to be in contention with the fact that any being can only be tempered once. So it's clear that the tempering effect in itself confers some level of protection against further alteration.

Is it because we freely choose it, recognizing that her will is benevolent? Or is it because we're compelled to, because of the blessing?

Whether or not big crystal mom is lying or not, I don't find it that hard to imagine the WoL willing to defend their own world seeing how they're currently busy living in it. I can't recall it clearly, but I'm of the impression that the Ascians' plans would result it something akin to the heat death of the (XIV) universe. Besides, it really feels like WoL & Co. haven't been doing much world-scale defending as of late - not that I mind. Most of the adventures of late involve post-war cleanup in one sense or another. Sure there's an Ascian being all Silence of the Lambs over at Garlemald, but that feels like a problem for future WoL.